What is the purpose of the command 'ebgp-multihop'?

The command 'ebgp-multihop' is used to set the maximum number of hops a BGP (Border Gateway Protocol) update can traverse when using External BGP (eBGP) sessions. Typically, eBGP assumes that peers are one hop away, meaning they are directly connected. However, in scenarios where BGP peers are not directly connected (e.g., when connecting through multiple routers), the 'ebgp-multihop' command allows you to specify how many hops away the BGP peer is.

By configuring this command, you enable the BGP router to send and receive updates to and from a peer that is more than one router hop away, maintaining BGP peering across a wider network. This is particularly useful in cases where organizational policies dictate particular routing architectures or connectivity must extend beyond direct links.

Understanding this concept is vital for effectively managing BGP configurations in larger, more complex networks where indirect connectivity is common.